Delay detonator with by-pass explosive bolt system

ABSTRACT

A projectile having a main explosive charge and a single igniting means is provided with: a first firing train, comprising a delay composition, a series of intermediate explosive charges initially disconnected from the main charge, and an arming means, including a dispensable aerodynamic element, operatively connecting the igniting means with the main charge during the flight of the projectile; and a second firing train comprising a flash tube connecting the igniting means with an auxiliary charge or detonator disposed adjacent to the dispensable element, for explosively separating the dispensable element from the projectile after the element has performed its function and prior to explosion of the main charge.

United States Patent Wolterman 1 1 June 24, 1975 [54] DELAY DETONATORWlTl-I BY-PASS 3,792,662 2/1974 Wolterman 102/70 EXPLOSIVE BOLT SYSTEMPrimary Examiner-Verlin R. Pendegrass [75] Inventor. g gz g HuntingtonAttorney, Agent, or Firm-Nathan Edelberg; Robert P.

' Gibson; Thomas R. Webb [73] Assignee: The United States of America asrepresented by the Secretary of the Army, Washington, DC. {57] ABSTRACTA projectile having a main explosive charge and a sin- [22] Ffled' 1974gle igniting means is provided with: a first firing train,

[21] Appl. No.: 430,958

[52] US. Cl. 244/125; 102/4; 102/812 [51] Int. Cl. F4213 25/10 [58]Field of Search 102/2, 4, 712, 81.2, 244/325, 3.3

[56] References Cited UNITED STATES PATENTS 2,597,703 5/1952 Busacker 4244/325 2,750,888 6/1956 Wynn 102/812 3,710,715 l/1973 Hoofnagle 102/4comprising a delay composition, a series of intermediate explosivecharges initially disconnected from the main charge, and an anningmeans, including a dispensable aerodynamic element, operativelyconnecting the igniting means with the main charge during the flight ofthe projectile; and a second firing train comprising a flash tubeconnecting the igniting means with an auxiliary charge or detonatordisposed adjacent to the dispensable element, for explosively separatingthe dispensable element from the projectile after the element hasperformed its function and prior to explosion of the main charge.

9 Claims, 4 Drawing Figures PATENTEDJUN 24 ms SHEET DELAY DETONATOR WITHBY-PASS EXPLOSIVE BOLT SYSTEM The present invention is an improvementover the invention disclosed and claimed in my copending US. Pat.application, entitled Delay Detonator With By- Pass Explosive BoltSystem," Ser. No. 278,l28, filed Aug. 4, i972, and now US. Pat. No.3,792,662, of which the present application is a continuation-in-part.In that application, a dual detonator assembly similar to that to bedescribed herein, and including a single igniting means, two detonatorsand a delay charge, is used to first explode one detonator toexplosively separate a stabilizing tail component from the detonatorassembly and subsequently initiate the other detonator.

BACKGROUND AND SUMMARY OF THE INVENTION Explosive projectiles adapted tobe launched toward an enemy target are usually provided with suitablemechanisms or means for safing, delaying, arming and detonating the mainexplosive charge before or during flight, or at impact with the targetor other object. These mechanisms sometimes include a part or elementthat performs its function, e.g., aerodynamically, during the earlystages of flight, and subsequently interferes with the further flight orother operation of the projectile, and thus becomes dispensable.

An object of the present invention is to provide an explosive projectilehaving a main explosive charge a dispensable element and means forexplosively separating the dispensable element from the projectile afterit has performed its intended function and then exploding the maincharge.

In accordance with one feature of the the invention, the projectileincludes a hollow annular housing coning a main explosive charge andincluding an inner wall through which at least one explosive leadextends, a dispensable element, a single igniting means, a first firingtrain comprising within the inner wall and a delay means and a firstexplosive means connecting the igniting means and the explosive lead,and a second firing train including a flash tube connecting the ignitingmeans with a second explosive charge disposed adjacent to thedispensable element. The dispensable element may, for example, be anaerodynamic element forming a part of an arming means for completing thefirst firing train prior to initiation of the igniting means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial sectional view,taken on line II of FIG. 2, of an explosive projectile incorporating thepresent invention, with the arming means in the safe position and thedispensable element in stowed position.

FIG. 2 is a top plan view of FIG. I.

FIG. 3 is a view similar to FIG. 1, showing the arming means in thearmed position and the dispensable element in axially extended position,prior to separation from the projectile.

FIG. 4 is a fragmentary axial section view showing a portion of thestructure of FIG. 3 after separation of the dispensable element.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1 and 2 illustratethe invention incorporated in an explosive projectile 1 comprising are-entrant or annular metal housing 3 including an outer tubular wall 5and an inner tubular wall 7, and a circular rear end plate 9. Theannular space between the walls 5 and 7 is filled with a high explosivemain charge 11, e.g., of RDX (cyclonite). The projectile fuze comprisesone or more radial apertures 13 through the inner wall 7, intermediatethe ends thereof, each filled with a high explosive booster lead 15,e.g., of RDX or PETN (pentaerythritol tetranitrate), and operativelyconnecting the interior of wall 7 with the charge 11. The end plate 9has a central aperture 17 which surrounds the rear end 19 of wall 7. Theend plate 9 is clamped to the rear end 21 of outer wall 5 by means of ametal clamp member 23, which comprises an externally-threaded metal hub25, threaded into an intemally-threaded recess 27 in wall 7, and aperipheral flange 29, which is seated in an annuiar recess 31 in plate9. Spanner wrench holes 33 are provided in flange 29 for turning theclamp memher.

A detonator tube-flash tube assembly 35, comprising a metal detonatortube 37 and a metal flash tube 39, is axially and slidably mountedwithin the inner wall 7. Detonator tube 37 comprises a thick-walled reartubular portion 41, having an axial bore 43 in which the flash tube 39is fixed, and a thin-walled forward portion 45 integral with the rearportion 41 and spaced radially from flash tube 39 to form an annularpowder chamber 47 therebetween. Disposed within the chamber 47 are, fromfront to rear, a combustible delay element 49, e.g., an elongated pelletof black powder or a barium chromate-boron composition composed of about89% barium chromate, [0% boron and 1% vinyl alcohol acetate resin, anintermediate primary high explosive charge 51, e.g., of lead azide, anda secondary high explosive charge 53, e.g., of RDX or PETN. The reardetonator tube portion 41 comprises an external threaded part 55 whichengages internal threads 56 on the clamp member 23, for movably mountingthe detonator tube in the projectile. The detonator tube 37 is initiallypositioned as shown in FIG. I with the charge 53in the safe positiondisplaced axially (out-of-line) from the leads [5.

The detonator tube 37 is unscrewed rearwardly from the clamp member 23during the flight of the projectile by reaction of the air stream withan aerodynamic element in the form of a spiral spring 57, e.g., ofsteel, having a flat inner end 59 mounted, with a reinforcing plate 61,in a transverse slot 63 in an extension 65 of the detonator tube. Theend of the extension 65 is peened over at 66 to close the detonator tube37 and hold the end 59 in the slot 63.

Prior to launch, the spiral spring 57 is retained, in the flat positionshown in FIG. 1, in a circular recess 67 in end plate 9, by engagementwith a portion of the projectile launcher, or the adjacent end of asimilar projectile stacked therewith. During launch, the restraint isremoved, and the spring 57, which is pre-formed to a conical spiralshape, springs out of the recess 67 into the conical shape shown in FIG.2. Then, due to the difference in air drag on the projectile and spring,the air stream causes the spring to rotate relative to the projectile,unscrewing the threaded end 55 from the threads 57 and moving thedetonator tube 37 rearwardly to the free-spinning, armed position, shownin FIG. 2, wherein a reduced diameter portion 69 of detonator tube 37clears the threads 57 and the charge 53 is located adjacent to and inline with the leads 15. A single igniting means 71 is mounted within theinner wall 7, as by means of a metal plug 73, in front of and exposed tothe forward ends of the delay element 49 (and the flash tube 39), forinitiating the burning of the delay element. Another function of thespring 57 is to stabilize the flight of the projectile after extensionof the spring to its conical shape. Thus, the arming means of the fuzecomprises the lead 15, the axially-movable detonator tube 37, thethreads 56 and the rotatable spring 57.

The structure described thus far (without the flash tube 39) may belaunched either as a single projectile from a gun barrel or other launchtube or as one of a plurality of sub-projectiles from a multiple-warheadprojectile. in either case, the igniting means 71 may be initiated atimpact with a target by any conventional means. The projectile orsub-projectile may be of the rebounding" type comprising a forwardimpacting part, a rear explosive part and a propelling charge interposedbetween the two parts adapted to be ignited at impact with the ground,for example, to propel the explosive part backwardly, for explosion at adesired height after a predetermined time delay produced by the delayelement 49. it has been found that, when the rear part of the projectile1 with its extended arming spring 57 rebounds as described, thenowforwardlyextending spring 57, which has performed its intendedfunction of arming the fuze, interferes with the stability of therebounding part. Therefore, in accordance with the present invention:the flash tube 39 is added, extending co-axially from the forward end ofdetonator tube 37 to the rear end of threaded portion 55; and explosivecharges, including an intermediate primary high explosive charge 75,e.g., of lead azide, and an explosive-bolt-type charge 77, e.g. of RDXor PETN, are positioned within the flash tube 39 adjacent to thethreaded portion 55, for explosively separating the spring 57 from theprojectile immediately after impact. Upon impact and the initiation ofthe igniting means 71, the flash therefrom substantially simultaneouslyinitiates the delay element 49 and the intermediate charge 75, whichimmediately detonates the explosive-bolt charge 77. The explosion ofcharge 77 ruptures the flash tube 39 and threaded portion 55 as shownschematically at 79 in FIG. 4, thus effectively separating the spring 57from the projectile. Where the projectile is of the rebounding" type,the propelling charge thereof may be the igniting means 71. in otherprojectiles, the igniting means 7] may be a conventional percussionprimer with conventional firing means. Tests have shown that theexplosive-bolt function occurs about 0.0003 second after ignition ofigniting means 71. Meanwhile, the delay element 49 continues to burn,eventually igniting the intermediate charge 51, which in turn detonatesthe secondary charge 53, to inltiste the leads I! and main chsrge ii. intests of three examples with different delay elements of bariumchromsteboron delay composition, the overall functioning times of thefiring train including the igniting means 71 and the charges 49, Si, 53snd 15, were 0.0l7, 0.106 and 0.230 second, respectively.

The foregoing disclosure and drawings are merely lllustrstive of theprinciples of this invention and are not to be interpreted in s limitingsense. i wish it to be un= derstood that I do not desire to be limitedto exact details of construction shown and described for obviousmodifications will occur to a person skilled in the art.

Having thus fully described the invention, what is claimed as new anddesired to be secured by Letters Patent of the United States is:

l. in an explosive projectile comprising a hollow annular housingcontaining a main explosive charge and including an inner wall throughwhich at least one explosive lead extends, a single igniting means and adispensable element adapted to be separated from the projectile after ithas performed its function but before the main explosive charge isexploded, a fuze comprismg:

A. a first firing train mounted within said inner wall and comprisingcombustible delay means and first explosive means interposed between andconnecting said igniting means with said explosive lead, for initiatingsaid main explosive charge at a predetermined time after ignition ofsaid igniting means; and

B. a second firing train comprising second explosive means disposedadjacent to said dispensable element for separating said element fromsaid projectile, and means connecting said igniting means with saidsecond explosive means for initiating the latter immediately afterignition of said igniting means.

2. A fuze as in claim 1, further including a hollow member within saidinner wall containing said delay means and said first explosive means atone end thereof; said connecting means comprising a flash tube extendingcoaxially through said hollow member and containing said secondexplosive means near the other end of said member; and said dispensableelement being removably attached to said other end of said member.

3. In an explosive projectile comprising a housing containing a mainexplosive charge and a single igniting means spaced from said maincharge, a fume including:

A. a first firing train for exploding said main charge comprising acombustible delay element exposed to said igniting means, firstexplosive means exposed to said delay element but initially disconnectedfrom said msin charge, and an means for operably connecting said firstexplosive means with said main chsrge during the flight of saidprojectile, said arming means including s dispensable part; and

B. a second firing train comprising second explosive means disposedadjacent to said dispensable part of said arming means, and meansconnecting said lgniting means with said second explosive means; wherebysaid igniting means, when ignited at s predetermined time sfteroperation of said arming means, simultaneously ignites ssld delayelement, for exploding said msin charge after s predetermined timedelsy, and initiates said second explosive means, to separate saiddispensable part of said srrning means from said projectile.

4. A fuze as in cldm 3, wherein said dispensable part of ssid armingmeans is sn aerodynamic element ex posed to the sir stream during theflight of said projsc= tile for actuating ssid arming means to am saidfirst fir ing trsin prior to the ignition of ssid igniting means.

5. A fuss as in claim 3, further including a hollow member containingsaid delay element and said first sx= plosivs means at one end thereof,and a flash tubs dis= posed cosxiaily within said hollow member and comraining said second explosive means near the othsr and of said member.

6. A fuze as in claim 5, wherein said housing is annular; and saidarming means comprises an explosive lead extending through the innerwall of said housing, and means connecting said hollow member to saidhousing for movement of said member between unarmed and armed positionswherein said first explosive means is misaligned and aligned,respectively, with said explosive lead.

7. A fuze as in claim 6, wherein said hollow member is threadedlyconnected to said housing for axial movement between said two positions,and said dispensable part of said arming means is an aerodynamic elementattached to said other end of said hollow member and adapted to berotated by the air stream during the flight of the projectile to movesaid member axially from the intermediate charge.

# i i i I.

1. In an explosive projectile comprising a hollow annular housingcontaining a main explosive charge and including an inner wall throughwhich at least one explosive lead extends, a single igniting means and adispensable element adapted tO be separated from the projectile after ithas performed its function but before the main explosive charge isexploded, a fuze comprising: A. a first firing train mounted within saidinner wall and comprising combustible delay means and first explosivemeans interposed between and connecting said igniting means with saidexplosive lead, for initiating said main explosive charge at apredetermined time after ignition of said igniting means; and B. asecond firing train comprising second explosive means disposed adjacentto said dispensable element for separating said element from saidprojectile, and means connecting said igniting means with said secondexplosive means for initiating the latter immediately after ignition ofsaid igniting means.
 2. A fuze as in claim 1, further including a hollowmember within said inner wall containing said delay means and said firstexplosive means at one end thereof; said connecting means comprising aflash tube extending coaxially through said hollow member and containingsaid second explosive means near the other end of said member; and saiddispensable element being removably attached to said other end of saidmember.
 3. In an explosive projectile comprising a housing containing amain explosive charge and a single igniting means spaced from said maincharge, a fuze including: A. a first firing train for exploding saidmain charge comprising a combustible delay element exposed to saidigniting means, first explosive means exposed to said delay element butinitially disconnected from said main charge, and an arming means foroperably connecting said first explosive means with said main chargeduring the flight of said projectile, said arming means including adispensable part; and B. a second firing train comprising secondexplosive means disposed adjacent to said dispensable part of saidarming means, and means connecting said igniting means with said secondexplosive means; whereby said igniting means, when ignited at apredetermined time after operation of said arming means, simultaneouslyignites said delay element, for exploding said main charge after apredetermined time delay, and initiates said second explosive means, toseparate said dispensable part of said arming means from saidprojectile.
 4. A fuze as in claim 3, wherein said dispensable part ofsaid arming means is an aerodynamic element exposed to the air streamduring the flight of said projectile for actuating said arming means toarm said first firing train prior to the ignition of said ignitingmeans.
 5. A fuze as in claim 3, further including a hollow membercontaining said delay element and said first explosive means at one endthereof, and a flash tube disposed coaxially within said hollow memberand containing said second explosive means near the other end of saidmember.
 6. A fuze as in claim 5, wherein said housing is annular; andsaid arming means comprises an explosive lead extending through theinner wall of said housing, and means connecting said hollow member tosaid housing for movement of said member between unarmed and armedpositions wherein said first explosive means is misaligned and aligned,respectively, with said explosive lead.
 7. A fuze as in claim 6, whereinsaid hollow member is threadedly connected to said housing for axialmovement between said two positions, and said dispensable part of saidarming means is an aerodynamic element attached to said other end ofsaid hollow member and adapted to be rotated by the air stream duringthe flight of the projectile to move said member axially from theunarmed position to the armed position.
 8. A fuze as in claim 7, whereinsaid element is a spiral spring having its inner end rigidly attached tosaid hollow member.
 9. A fuze as in claim 3, wherein: said firstexplosive means comprises an intermediate primary high explosive elementadjacent to said delay charge, and a secondary high explosive chargeadjacent to said intermediate charge; and saiD second explosive meanscomprises a second intermediate primary high explosive charge exposed tosaid igniting means through said flash tube, and an explosive-boltcharge adjacent to said second intermediate charge.